Breeding Of Tree Species Research Articles

Performance of Seven Tree Breeding Strategies Under Conditions of Inbreeding Depression.

In the domestication and breeding of tree species that suffer from inbreeding depression (ID), the long-term performance of different breeding strategies is poorly known. Therefore, seven tree breeding strategies including single population, subline, selfing, and nucleus breeding were simulated using a multi-locus model with additive, partial, and complete dominance allele effects, and with intermediate, U-shaped, and major allele distributions. The strategies were compared for genetic gain, inbreeding accumulation, capacity to show ID, the frequencies and fixations of unfavorable alleles, and genetic variances in breeding and production populations. Measured by genetic gain of production population, the nucleus breeding and the single breeding population with mass selection strategies were equal or superior to subline and single breeding population with within-family selection strategies in all simulated scenarios, in spite of their higher inbreeding coefficients. Inbreeding and cross-breeding effectively decreased ID and could in some scenarios produce genetic gains during the first few generations. However, in all scenarios, considerable fixation of unfavorable alleles rendered the purging performance of selfing and cross-breeding strategies ineffective, and resulted in substantial inferiority in comparison to the other strategies in the long-term.

Vegetative Propagation Techniques-A Potential Tool for Yield Improvement in Forestry

Ever increasing demand for forest produce necessitates urgency to improve the productivity of the forest. Tree breeding and propagation technologies serve as important tools in tree improvement programs. However, breeding of tree species for sustainable gain takes years or even decades and seed raised plantation of any species is bound to exhibit variations in growth and other characteristics. Propagation by vegetative means assumes importance when desirable biotypes need to be multiplied in a short span of time. In this paper vegetative propagation techniques of tree species for higher biomass yield are discussed.